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Analyzers Provide Water Security in Space and on Earth

Saturday, 01 January 2011

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NASA Technology

Resourcefulness is a key quality for living in space,
and on the International Space Station (ISS),
that means making the most of water supplies. In
2008, the installation of the Water Processing Assembly
(WPA) onboard the ISS allowed the space station’s crew
to do just that. The WPA purifies moisture from nearly
every possible source—sweat, water vapor, wastewater,
and even urine—for drinking and oxygen generation.
Capable of producing 35 gallons of potable, recycled
water a day, the system has reduced the need for water
delivered to the ISS by over 1,000 gallons a year, saving
significant payload costs in the process.

As with any drinking water, quality is a concern,
particularly when that water has been recycled. This
is an issue of particular interest in space, where ISS
crewmembers would have to deal with any illness far from
the nearest medical personnel and facilities. The WPA
employs sensors that monitor water quality by measuring
its conductivity, and rounding out the system’s quality
assurance methods is a device developed for NASA by a
private industry partner. That company has now made
the technology available for ensuring the purity of water
for consumption and industrial uses on Earth.

Partnership

Known as a total organic carbon analyzer (TOCA),
this device measures organic carbon levels in water, a key
indicator of water quality, as carbon is present in most
dangerous contaminants. Prior to the installation of the
WPA, the ISS had a commercial TOCA onboard, but that
technology did not fully satisfy NASA’s requirements. To
develop a better solution to ensure the potability of the
WPA’s recycled water, NASA contracted OI Analytical
of College Station, Texas, in 2006. Working in conjunction
with Wyle Laboratories, the company had proposed
an advanced TOCA device that provided fast, effective
monitoring of TOC levels while eliminating aspects of
the technology that made it impractical for space applications.

The resulting Proto-flight Unit, or PFU1, proved to
be the innovative breakthrough NASA needed to fully
enable the WPA. Detection of TOC in water requires an
oxidation process that standard TOCAs generate using
either expensive, hazardous chemicals or through high
temperature combustion—neither feasible for an environment
like the ISS. OI devised an electrochemical solution
to create oxidation using the water itself. By applying an
electrical voltage to a composite electrode in the oxidation
chamber of the analyzer, the TOCA breaks down
the water sample, forming hydroxyl radicals that in turn
break down any organic molecules into carbon dioxide
and water. The analyzer’s infrared detector then measures
the concentration of carbon dioxide to provide an accurate
assessment of the water’s organic carbon content.

“The original prototype was at a level that allowed us
to save two years in the development process,” says Gary
Erickson, research and development manager for the
TOCA project. This in turn allowed NASA to implement
the WPA ahead of schedule. With the system’s recycling capabilities and now fully redundant safety measures, the
ISS not only required fewer water deliveries, but it was
also able to realize its full crew capacity—increasing from
three members up to six.

Benefits

OI recognized the potential for its NASA technology as
a commercial solution. Adapting it for terrestrial use, the
company now sells the electrochemical-oxidation device
as its 9210e On-Line Total Organic Carbon Analyzer.
The NASA-derived system provides a host of benefits for
water quality applications ranging from municipal and
industrial water treatment to feed water and condensate
return in turbines and boiler systems.

“Essentially any place where large amounts of water
are used, from the cleanest to the most contaminated, the
need to measure organic carbon exists,” says Erickson, also
market manager for the TOCA technology, “but the costprohibitive
nature of the technology kept it from being
mandated in a number of areas, and it kept commercial
companies from utilizing the technology.”

Question of the Week

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